PCIe Compatibility Negotiation between Host and Peripheral

[RamaManikandan]

I have a Clarification and doubt

Clarification: If a host has only PCIe v3 slot can we connect a Peripheral which is only PCIe v2 supported? And if it can be connected then the communication between host and peripheral happens in v2 or v3?

Doubt: (Assuming PCIe v2 Peripheral can be connected to PCIe v3 Host and communication happens at v2). When a PCIe v2 peripheral is connected to only PCIe v3 supported Host the communication happens at v2.

How does the host knows host know that the peripheral connected is v2 and the communication need to be held at v2 specifications?

How "Negotiation happens between Host and the Peripheral" about on which version of PCIe the communication is to be held between the host and peripheral?

[AndrewG_Intel]

Hello @RamaManikandan

Thank you for posting on the Intel® communities.

In order to provide you with the proper information, could you please provide the following details?

1- Is this inquiry regarding PCIe lanes of Processors? Could you please confirm the processor model(s) regarding your concerns?

2- Details about your motherboard or PC system: (brand, model, etc).

3- Why are you looking for this information? Are you experiencing any specific errors? Or are you trying to achieve any specific goal?

Best regards,

Andrew G.

Intel Customer Support Technician

[RamaManikandan]

Thanks for your reply AndrewG_Intel

This query is not regarding PCIe Lanes of Processor 

It is about general negotiation between Host and the peripheral when both operating at different versions. Like mentioned in the question How will the host will be came to know that the Peripheral connected will support only PCIe v2 and communicate in PCIe v2?

[AndrewG_Intel]

Hello RamaManikandan

Thank you for your response.

Our chances to provide information about PCIe (Peripheral Component Interconnect Express) for all peripherals and systems (in general) are limited since we don't know how all of them have been designed. If when you say "v2 and v3" you are referring to PCIe versions (e.g PCI 2.0 and 3.0) and not referring to voltages, we are not allowed to provide more accurate information since this is not regarding a particular Intel® product but what we can say is that the standards of these two versions are backward compatible. (If you are referring to voltages, please clarify).

Regarding your specific inquiries and for additional information in case you have a specific product, our recommendation is to contact the device/computer manufacturer (OEM) for more details and clarification. This is since we cannot confirm if this standard is met/achieved in a particular system due to customizations, limitations, technologies, and so on. If this is regarding a specific Intel® product, please kindly provide us with the motherboard/system/CPU model.

Best regards,

Andrew G.

Intel Customer Support Technician

[RamaManikandan]

Thanks for the reply

[AndrewG_Intel]

Hello RamaManikandan

You are welcome, thank you for your response. For any other inquiries please do not hesitate to contact us again.

Best regards,

Andrew G.

Intel Customer Support Technician

[AndrewG_Intel]

Hello RamaManikandan

We have not heard back from you so we will proceed to close this thread now. If you need any additional information, please submit a new question as this thread will no longer be monitored.

It has been a pleasure to assist you.

Best regards,

Andrew G.

Intel Customer Support Technician